614 REPRODUCTION. 



The other relations between different parts of the structure remain the 

 same. 



The corpus luteum has now attained its maximum of development, 

 and continues without very perceptible alteration during the fifth and 

 sixth months. It then begins to retrograde, diminishing in size during 

 the seventh and eighth months. Its external wall becomes still more 

 faded, changing to a faint yellowish-white color, not unlike that pre- 

 sented at the end of the third week. It is thick, soft, and elastic, and 

 numerous slender blood-vessels can be seen 

 FIG. 175. penetrating from without into the interstices 



of its convolutions. Its central coagulum is re- 

 duced to the condition of a whitish radiated 

 cicatrix. 



Its atrophy continues during the ninth month. 

 At the termination of pregnancy (Fig. 175) it 

 is reduced to 12 or 13 by 10 millimetres in diam- 

 eter, and its weight to about 500 milligrammes. 

 It is of a faint indefinite hue, but little con- 

 trasted with that of the surrounding tissue. 

 The central cicatrix is very small, and appears 

 only as a thin whitish lamina, with radiating 

 processes. The whole mass is still firm to the 

 touch, and readily distinguishable, both from its 

 CORPUS LUTEUM of pregnancy, size and texture, as a prominent feature in 



a term, from a woman dead the ovar i an tisSUC. The Convoluted Structure 

 in delivery from rupture of 



the uterus. of the external wall is very perceptible, and 



the point of rupture, with its peritoneal cica- 

 trix, distinctly visible. 



After delivery, the corpus luteum rapidly retrogrades. At the end 

 of eight days it usually weighs less than 300 milligrammes, and in 

 about two months its color is no longer distinguishable, although indi- 

 cations of its convoluted structure may still be discovered by close 

 examination. These traces of its existence remain for a long time 

 afterward, more or less concealed in the ovarian tissue ; being some- 

 times perceptible so late as nine and a half months after delivery. They 

 finally disappear entirely, together with the external cicatrix which 

 marked their situation. 



During pregnancy, owing to the suspension of ovulation and the 

 quiescence of the Graafian follicles, no new corpora lutea are produced ; 

 and as those which were formed before the period of conception fade 

 and disappear, the corpus luteum which marks the occurrence of preg- 

 nancy after a time exists alone in the ovary. 



In twin or triplet pregnancies we should, of course, find a corre- 

 sponding number of corpora lutea in the ovaries ; and it is evident 

 that two Graafian follicles might rupture simultaneously at the time 

 of conception, and but one of the eggs become impregnated or reach 

 maturity. In that case there might be one foetus in the uterus and 

 two corpora lutea in the ovaries. But in such instances both corpora 



